The objectives of these Studies are: to investigate the relationships of biologic, genetic, medical, and environmental factors in the parents--including events in pregnancy, labor, and delivery--to the normal and abnormal development of the offspring: to investigate the relationships of these factors to pregnancy loss in the form of early fetal death, perinatal mortality, infant and childhood mortality, and to incidence of congenital anomalies: to provide detailed growth curves for children suitable for the study of differences in growth rate according to the above factors: to provide estimates of illness and injury rates in infants and children: to accumulate a large number of matings in which the detailed blood group typings in the different systems are known for the woman, her husband, and the offspring, suitable for investigation of blood groups incompatibilities producing potential disease in the infant: to investigate the relationships of physical and mental developments in early childhood to those during the period of puberty and adolescence. The investigations are conducted on members of the Kaiser Foundation Health Plan--a prepaid medical health plan--who reside in the San Francisco East Bay area. Information was obtained from the gravida early in pregnancy on a number of medical, biologic, and environmental factors. Blood typings in seven systems was obtained on the gravida, her husband, and the cord blood of the infant. Some four samples of blood were frozen and kept in cold storage. The method of study is longitudinal for both mother and child. In addition to information obtained specifically for the studies, the medical records for the gravida and child provided information on illnesses, conditions, injuries, and drugs. A special battery of tests was given the child on his fifth birthday. These include vision, hearing, speech, and intelligence tests.